Carmichaelia stevensonii
Common name
Weeping tree broom, cord broom
Synonyms
Chordospartium stevensonii Cheeseman
Family
Fabaceae
Flora category
Vascular – Native
Endemic taxon
Yes
Endemic genus
No
Endemic family
No
Structural class
Trees & Shrubs - Dicotyledons
NVS code
The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.
CARSTE
Chromosome number
2n = 32
Current conservation status
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2017 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2012 and replaces all previous NZTCS lists for vascular plants. Authors: By Peter J. de Lange, Jeremy R. Rolfe, John W. Barkla, Shannel P. Courtney, Paul D. Champion, Leon R. Perrie, Sarah M. Beadel, Kerry A. Ford, Ilse Breitwieser, Ines Schönberger, Rowan Hindmarsh-Walls, Peter B. Heenan and Kate Ladley.
2012 | Threatened – Nationally Endangered | Qualifiers: RF, RR
Previous conservation statuses
2009 | Threatened – Nationally Endangered | Qualifiers: RF, RR
2004 | Gradual Decline
Brief description
Rare small tree with weeping leafless twigs inhabiting south Marlborough Valleys. Bark on young branches with orange stripes. Twigs 2mm wide, grooved, rounded, drooping. Flowers white with purple streaks, in drooping spikes. Fruit a small dry sharp-tipped hairy pod containing a single hard seed.
Distribution
Confined to inland river valleys of South Marlborough.
Habitat
In low scrub or sparsely vegetated sites overlying free draining colluvial or alluvial soil, rockland, and steep mountain slopes.
Features
Leafless tree to 8-10 m tall with stout, sparingly branching trunk to 400 mm diameter and compact canopy of drooping, pendulous branchlets. Branches stout, initially erect soon drooping; grey-brown when mature, with relatively smooth bark and conspicuous raised rings at nodes; actively growing branches yellowish-grey to yellow-green with dark orange striae; bark chartaceous. Branchlets numerous, pendulous, striate, deeply grooved, subterete to 2 mm diameter yellowish-grey to grey-green. Stipules clasping shoot, 0.5 × 0.3 mm, elongate-triangular, pointed, tomentose on undersides, chartaceous, eventually fraying off with age. Leaves early deciduous, simple, emarginate, alternate, initially folded along midrib but gradually expanding and increasing in size to c.9 × 6 mm, sparsely hairy on upper surface, more densely so on undersides; petioles hairy, fleshy, ± cylindric, to 3 mm long. Leaves reduced to scales on mature shoots. Inflorescences in simple, lateral, pendulous compact, densely-flowered racemes up to 100 mm long; racemes solitary or in fascicles on peduncles arising directly from nodes on mature branchlets, mostly drooping. Occeasionaly erect or with the tips ascending. Flowers c.9 × 6 mm; pale lavender, with darker veins and markings. Peduncles pilose; pedicels c.0.5-0.9 mm long, pilose, arising in axils of peduncle scales. Rim and outer surface of calyx tube pilose. Petals whitish with intense lavender or violet markings towards base of standard and keel; veins of all petals dark lavender; standard orbicular, longer than wings, with margins reflexed; wings dolabriform, falcate, obtuse < keel, keel incurved, obtuse, ± the same length as the standard. Ovary sericeous; style long, slender, incurved, glabrate; stigma glabrous; ovules c.5. Pod turgid, rhomboid to suborbicular; immature pods grey-green, style often long-persistent, breaking off near its base leaving a stout, blunt, slightly upturned beak c.1 mm long; mature pod subcoriaceous, stramineous, densely hairy, obliquely obovate, 6 × 3-4 mm including beak; the withered calyx, corolla and stamens remaining long-attached to the pod base. Seeds reniform, oblong or triangular, 1-3 per pod, yellow-green, dark yellow, brown, orange, orange-brown or red-brown, spotted grey brown, red-brown or black, rarely unspotted, 1.7-2.0 mm.
Similar taxa
Carmichaelia stevensonii is distinguished from C. muritai (A.W.Purdie) Heenan, by the yellow-green, drooping branchlets and flower clusters. Actively growing branchlets of this plant have very distinctive bark with vertical orange stripes. C. muritai branches are initially erect with the apices drooping, the inflorescences are erect, the flowers 4 × 4 mm; whitish with intense purple-violet markings rather than whitish with lavender markings; the pods are 3.5 × 1.8 mm (cf. 6 × 3-4 mm), and usually 1-seeded rather than 1-3 seeded.
Flowering
December - January
Flower colours
Violet/Purple, White
Fruiting
March - May
Life cycle
Seeds are possibly dispersed by wind and granivory (Thorsen et al., 2009).
Propagation technique
Easy from fresh seed. Can be grown with some difficulty from semi hardwood cuttings. Dislikes humidity and once established should not be moved.
Threats
Under serious threat from browsing animals such as wild goats. At some lower altitude sites little regeneration is happening due to introduced grasses which outcompete seedlings and colonise fresh disturbed ground in which seedlings would normally germinate. Recent field surveys suggest this species is much more threatened than had previously been believed.
Etymology
carmichaelia: After Carmichael, a botanist
Attribution
Description based on fresh flowering material and herbarium specimens.
References and further reading
Thorsen, M.J.; Dickinson, K.J.M.; Seddon, P.J. 2009: Seed dispersal systems in the New Zealand flora. Perspectives in Plant Ecology, Evolution and Systematics 11(4): 285-309.